Henby huntings



(No Model.)

H. HUN NINGS.

TELEPHONE TRANSMITTER.

No. 250.250. Patented Nov. 29,1881.

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HENRY HUNNINGS, OF ROTHWELL, COUNTY OF YORK, ENGLAND.

TELEPHONE-TRANSM ITTER.

SPECIFICATION forming part of Letters Patent No. 250,250, dated November 29, 1881.

Application filed September-30, 1881. (No model.) latented in England September 16,1678.

To all whom it may concern:

Be it known that I, HENRY HUNNINGS, of Rothwell, in the county of York, England, have invented a new and useful Improvement in Telephone Transmitters, which improvement is fully set forth in the following specification.

The invention relates to telephones which are used in connection with a battery or other suitable source of electricity, and operate to throw the electric current into undulations corresponding to the sound-waves representing articulate speech or other sounds by varying the resistance of the battery-circuit, these instruments being comprised under the name of telephone-transmitters or variable-resistance telephones.

The present invention has reference to the tension-regulator or variable-resistance medium in said telephones.

In the transmitters heretofore commonly used the tension-regulator consists of two or more solid electrodes, of metal or of carbon, with their surfaces in contact, or a button of compressed and consolidated material, such as lamp-black, the variations in resistance being efi'ected by the variations in pressure between the electrodes or upon the conducting-button. Fibrous material coated with conducting particles ofcarbon has also been used.

In the present invention particles of conducting material in a loose and free state are used, the same being included in the electric circuit and combined with a vibratory plate or diaphragm for receiving the sound-waves, and for producing by its vibrations the variations in resistance of said particles. The loose particles of conducting matter are found to be most delicately sensitive to sonorous vibrations, and they possess the further ad vantage that they form a tension-regulator of low resistance, and that the transmitters containing the same can be made very compact, can be freely handled without liability of being injured, and do not require to be delicately adjusted for successful operation.

The accompanying drawing, which forms a part of this specification, shows in section a transmitter embodying the invention.

A is a vibrating diaphragm, made very thin, preferably of platinum-foil, though thin ferrotype-iron, silver, or other conducting material may be used, being fixed, as shown, or in other suitable manner, so as to be capable of vibrating freely. It is kept in place in the case D by a ring, F. v

B is the back plate, of brass or other suitable metal, the intervening space being filled with loose finely-divided conducting material C. The most advantageous results proceed from the use of carbon, and particularly of oven-made engine-coke crushed very finely, not ground, so as to pulverize (not shear or tear) the particles. Metallized carbon-powder prepared with mercury or other suitable metal may, however, be used, if desired.

E E are the binding-screws, placed in connection with diaphragm A and back plate, B.

The instrument is placed in circuit with a voltaic battery and receiving telephone of suitable construction-such as Bells-and the words or other sounds, made close or otherwise to the instrument, will be distinctly and loudly reproduced at the receiving-instrument.

The diaphragm A, back plate, B, and case D may be altered in form, and made oval, square, or of other suitable shape, if desired; but the best results are produced if the instrument be made circular.

When the instrument is held in the hand at a convenient angle for speaking into it-say inclined from the vertical about twenty-five degrees-the weight of the particles generally packs them sufficiently, even if the chamber be not absolutely full, but has a pinch of the material taken out after filling. The handling to which the instrument will be subjected if used as a hand instrument will ordinarily keep the filling in good condition; or if by accident it becomes too tightly wedged, turningit upside down or striking it with the palm of the hand will generally restore it to the proper state.

It is obvious that the details of construction may be indefinitely varied without departing from the spirit of the invention.

Other suitable conducting material can be used iri place of carbon.

The diaphragm can be made of metal-cov cred material, instead of wholly of metal; or a 100 vibrating strip or plate can be attached thereto.

Having now fully described my said inven-- tion and the manner of carrying the same into effect, I would observe, in conclusion, that no claim is made herein to carbon specifically, in contradistinction to other conducting material, as this is claimed in Letters Patent No. 246,512, granted to me August 30, 1881; but

What I do claim herein is, broadly- 1. As a tension-regulator or means for varying the resistance in a telephonic transmitter, finely-divided conducting material in a loose and free state, substantially as described.

2. The combination, with a body of finelydivided conducting material in a loose and free state, of a vibratory plate or diaphragm for varying the resistance of said body, sub- 15 stantially as described.

In testimony whereof I have signed this specification in the presence of two subscribing Witnesses.

HENRY HUNNINGS. 

